Truck cabs are conventionally constructed from a multitude of formed sheet metal pieces that are held by suitable fixtures for welding to each other. Normally, such assembly proceeds by first fabricating side door frames which are then welded between a floor pan and a roof to provide the occupant compartment of the truck cab. Such welded steel constructions have been utilized for many years. See, for example, the various sheet metal vehicle body constructions disclosed by U.S. Pat. Nos.: 1,608,228 Parke et al; 1,834,525 Ledwinka; 2,186,689 Wendt; 2,383,417 Renno; and 2,520,074 Wernig et al.
Attempts have previously been made to replace conventional formed sheet metal vehicle body constructions with other materials. See, for example, U.S. Pat. No. 2,192,075 Gregire which utilizes cast pieces of aluminum.
Synthetic plastic materials have also previously been utilized for vehicle body constructions such as disclosed by U.S. Pat. Nos.: 3,596,979 Hablitzel et al; 4,695,342 Belleau et al; and 4,730,870 DeRees.